Loop thrower



Dec. 10, 1963 w. J. HILL ETAL 3,113,477

LOOP THROWER Filed Dec. 17, 1959 5 Sheets-Sheet l INVENTORS William 3. Hill BenJamin R. 7l eely H 'rne Dec. 10, 1963 w. J. HILL ETAL LOOP THROWER 5 Sheets-Sheet 2 Filed Dec. 1'7, 1959 JNVENTORS William 3. Hill 71 R-Tleel" B en Jami H 'rney Dec. 10, 1963 w, J. HILL ETAL 3,113,477

LOOP THROWER Filed Dec. 17, 1959 5 Sheets-Sheet 3 2a I9 I8 INV EN TORS I 4 William 3. Hill.

yBenJamin R Tleely wmM H o neg Dec. 10, 1963 w. J. HILL ETAL LOOP THROWER 5 Sheets-Sheet 4 Filed Dec. 17, 1959 5 a m m MH O W n mm/B I. v i wB Y B Dec. 10, 1963 Filed Dec. 17, 1959 5 Sheets-Sheet 5 REFERENCE VOLTAGE 250 V. D.C.

WITH IMPACT LOOP ADJUSTMENT 0 w E REQUIRED tr) STEADY STATE ROLLING SPEED l! \'1 LOOP THROWER E WITHOUT SPEED IMPACT LOOP o ADJUSTMENT ADJUSTMENT 1 Z INVENTORS 0 TIME ZI/I'ZZjam F/I'ZZ BY BenJamIn R. TZeeZy H or e3 United States Patent 3,113,477 L001 THROWER Wiliiam I. ma, Worcester, and Benjamin R. Neely, West Boyistc-n, Mass, assignors to Morgan Construction Company, Worcester, Mass, a corporation of Massachusetts ll iied Dec. 17, 1959, Ser. No. 860,221 2 Claims. (Cl. 80-35) This invention relates to a loop thrower and more particularly to apparatus arranged to produce a vertical loop in rapidly-moving stock in a rolling mill.

Between the stands of a rolling mill it is sometimes necessary, because of the relative speeds of adjacent mill stands, to provide for a loop in the material being rolled. At the same time it is desirable to maintain the tension in the stock at a predetermined value, since the quality of the rolling depends to a considerable extent on the tension in the stock. Looping devices which have been provided in the past have furnished the loop, but have failed to maintain the tension in the stock at a fixed, predetermined value. These and other deficiencies in the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the present invention to provide a loop thrower which will maintain the tension in the stock at a predetermined value irrespective of the size of the loop.

It is another object of the present invention to provide an apparatus for forming a loop in stock in a rolling mill in which the size of the loop will be dependent upon the speed of the roll stand following the apparatus.

A further object of the present invention is the provision of a device for forming a loop in a vertical plane with a high level of force in the upward direction and with a much lower level of force in the downward direction.

It is another object of the instant invention to provide a loop thrower giving quick action in the upward direction which moves in the downward direction at a slower rate.

It is a further object of the invention to provide a loop thrower for forming a loop having a vertical height which is inversely proportional to the speed of the rolling mill following the apparatus.

With these and other objects in view as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to certain of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a side elevational view of a loop thrower embodying the principles of the present invention;

FIG. 2 is a plan view of the loop thrower;

FIG. 3 is a sectional view of the invention taken on the line III-III of FIG. 2;

FIG. 4 is an enlarged sectional view of the apparatus taken on the line lV-IV of FIG. 2;

FIG. 5 is a somewhat schematic view of pneumatic and electrical apparatus forming a part of the invention;

FIG. 6 is an electrical diagram of certain electrical apparatus associated with the invention; and

FIG. 7 is a graph showing certain phases of the operation of the invention.

Referring first to FIGS. 1, 2 and 3, which show the general features of the invention, the loop thrower, designated generally by the reference numeral 10, is shown as having a base 11 at the upper portion of which is mounted a guide 12 having vertically upstanding walls 13 and 14 adapted to lie on either side of the roll pass at the upper part of the base extending through the guide 12 is a shaft 16 which extends transversely of the pass line and which is mounted in pillow blocks 17 and 18 located at the upper part of the base. This shaft located at the upstream end of the guide and mounted on the shaft for swinging movement is an arm 19 whose downstream end is bifurcated and provided with a roller 21.

The details of mounting of the roller are shown in FIG. 4 and it can be seen that the outer end of the arm 19 is provided with a transverse shaft 22 on which the roller 21 is mounted by means of ball bearings, the shaft being fixed against rotation relative to the arm 19 and the roller having flanges at its end to retain stock without appreciable sideways slippage. As a matter of fact, the intermediate surface of the roller 21 is provided with two conical surfaces which have their minimum diameter at the center of the roll, thus providing for a centering action on stock.

The shaft 16 extends beyond the pillow block 18 and has keyed to it a crank arm 23. Fastened to the outer end of the crank-arm 23 is a bifurcated fitting 24 which is pivoted to that outer end and is fastened to the free end of a piston rod 25 associated with a pneumatic linear actuator 26 having a cylinder pivotally fastened to the base 11 by means of a pivoted cradle arrangement 27. The intermediate portion of the crank-arm 23 is attached to a bifurcated fitting 28 which is mounted at the outer end of the piston rod of a small hydraulic cylinder 29 which acts as a fluid damper or shockabsorber. Also keyed to the shaft 16 beside the crankarm 23 is a gear segment 31 which engages a pinion gear 32 mounted on a small shaft 33 mounted in its own pillow blocks 34 and 35 mounted on a lateral extension 36 of the base 11. The shaft 33 is connected with the input shaft of a reduction unit 37. The output shaft is connected to a tachometer generator 33. Referring particularly to FIG. 2 it can be seen that the gear segment 31 also contacts a pinion mounted on a small shaft 39 which is also suitably mounted in pillow blocks on the lateral extension 36 of the base 11. The outer end of the shaft 39 is connected to a selsyn 41.

Referring now to FIG. 5, which not only shows the pneumatic circuits but also shows the electrical control circuit for the pneumatic circuits, a very important element is the pneumatic linear actuator 26 with its piston rod 25 which serves to actuate the loop throwing arm 19. A pneumatic line 42 is connected to a source of air pressure, not shown, and to one side of a high-pressure regulating valve 43. An air line 44 leads from the other side of the valve 43 to one side of a lowpressure regulating valve 45. From the intermediate portion of the line 44 extends an air line 46 leading to a high-pressure solenoid valve 47. This valve is provided with an actuating coil 48 which coil must be energized to open the valve. An air line 49 extends from the opposite side of the valve 47 to a line 51 which is connected to the opposite side of the valve 45. The other end of the air line 51 is connected to a directional solenoid valve 52 which is shown as a double solenoid, pilot-operated, four-way valve. An air line 53 leads from the same valve grooving as the line 51 to the upper part of the linear actuator 26. A lower groove of the valve 52 is connected by an air line 54 to the lower part of the linear actuator 26. A line 55 is connected to the same valve groove as the: line 54 and leads to exhaust. The valve 52 is provided with an upactuating coil 56 and a down-actuating coil 57. Each one of these coils when energized actuates the valve in such a manner as to produce the named effect on the linear actuator piston rod 25. It should, perhaps, be noted at this point that the hydraulic cylinder 29 is provided with line and defining an open-topped passage 15. Mounted its own self-contained hydraulic circuit containing throttling valves and check valves in such a manner that it presents no resistance to movement of the crank arm 23 when the crank arm is moving in the downward direction but presents considerable resistance in the way of a motion-damping mechanism when the crank arm is moving in the upward direction and the arm 19 is moving in the downward direction.

Referring to the electrical diagram of FIG. 5, two power lines 58 and 59 are connected to 110 volt A.C. source. A line 61 extend from the power line 58 through a normally-open contactor 62 through the up-solenoid coil 56 through a normally open contactor 63 to the power line 59. A line 64 extends from the line 61 and the coil 56 and passes through the solenoid coil 48 and a normally open contactor 65 and returns to the line 61 between the coil 56 and the contactor 63. A line 66 extends from the power line 53 to a normally open contactor 67 through the down-solenoid coil 57 through a normally open contactor 68 to the power line 59. Now, the contaotors 67 and 68 form a portion of a relay having an actuating coil 69, while the contactors 62, 63, and 65 are joined together and actuated by a relay coil 71. The coil lies in a line 72 extending between a power line 73 and a power line 74, which are connected to :a source of 220 Volt D.C. current. The switch 75 is interposed in the line 72. In the same way the coil 71 lies in a line 76 connected between the power lines 73 and 74 and a switch 77 is interposed in the line. Now, the switches 75 and 77 are interrelated by a connecting means 78 so that when the switch 75 is open, the switch '77 is closed and vice versa. It will be understood that the switches 75 and 77 with the associated connecting means 78 may consist of photoelectric cells, switches, or any similar control means for satisfying the particular functional situation.

Referring now to FIG. 6, which shows a simplified elementary diagram of a rolling mill stand speed regulation with loop control, a line 79 is connected to a reference voltage and through a Vernier speed adjusting rheostat 81 to an impact loop adjusting rheostat 82. A normally-closed contactor 83 is connected from one side to the other of the rheostat 82. The elements 82 and 83 are followed by a coarse speed adjusting motor-operated rheostat 84 having an adjusting arm 85. The adjusting arm is connected to one end of reference windings 86 and 87 which are connected in series with each other and with the tachometer generator 88 on the mill motor. Lines 89 and 91 extend from the selsyn 41 on the loop thrower and are connected to a 110 volt A.C. source. The output of the selsyn is connected through a rectifier 92 the positive side of which is connected to the tachometer generator 38 on the loop thrower which is connected in series with loop control windings 93 and 94. They in turn are connected to an automatic loop control selector 95 of the conventional type. A center tap- 96 on the reference winding 86 is connected to an increasing speed amplistat 97 while a similar center tap 98 is connected to the center of the loop reference winding 87 and is connected to the declining speed amplistat 99. An output coil 101 associated with the increasing speed amplistat 97 and an output coil 102 associated with the declining speed amplistat 99 are connected by a center tap 103 to an amplidyne 104. This amplidyne is connected to the mill motor field coil 105 while the other side is connected through a coarse-speed motor-operated rheostat 106 and to a 250 volt DJC. source.

The operation of the apparatus will now be readily understood in view of the above description. The usual rolling mill is designed to operate with loops in the rolled stock between the final finishing stands of the mill. A loop thrower made in accordance with the present invention is mounted between two successive mill stands and, as has been shown, each of the loop throwers consist essentially of a roller mounted on a pivoted arm. When the loop thrower is in its down position, the roller is below the mill pass line and the product being rolled may pass unobstructedly from one stand to the next stand. When the loop thrower is in its up position the roller of the loop thrower rises to a position above the mill pass line. If the thrower is moved from its down position to its up position after the product has entered the mill stand following the loop thrower and if the speeds of the mill stands are correctly set, a vertical loop will be formed. After the arm 19 is raised to form a loop, a slight upward pressure is maintained to cause the loop thrower to follow the loop while the product is being rolled, thus maintaining the tension in the stock at a predetermined constant value. It will be noted hereinafter that this feature is used to maintain the height of the loop by controlling the speed of the mill stand following the loop thrower. Just before the rolled product leaves the mill stand ahead of the loop thrower, the loop thrower arm is lowered, thus preparing for the front end of the next bar. As is evident, the loop thrower arm 19 is raised and lowered by means of the double-acting, pneumatic, linear actuator 26 and the air cylinder is controlled by a four-way, double-solenoid-controlled, air valve 52 and a two-way spring-return, single-solenoid-controlled normally-closed, air valve 47.

Referring to the air diagram shown in FIG. 5, the purpose of the two air pressure regulators 43 and 45 is to permit setting two levels of air pressure, one level to cause the loop thrower to rise quickly and the other level to hold the roller against the loop. The air pressure regulator settings will depend upon the size and weight of the product being rolled and must be determined from operating experience.

The four-way valve 52 functions as a directional valve directing aid to the cylinder to cause the piston to rise or fall. The two-way valve 47 functions as a by-pass around the low-pressure regulation 45. During operation the coil 48 of the solenoid valve 47 will be energized momentarily each time the up-coil 56 of the valve 52 is energized. This will cause high-pressure air, as determined by the setting of the high pressure air regulator 43, to be admitted to the air cylinder to produce quick upward movement of the loop thrower. A short time later the high-pressure solenoid coil 48 will be de-energized to close the by-pass around the low pressure regulator 45, this by-pass including the air lines 46 and 49 as well as the valve 47. Air pressure is then determined by the setting of the low-pressure regulator 45 and this pressure is admitted to the air cylinder holding the loop thrower against the bar. High pressure is not required when lowering the loop thrower because the weight of the unit assists the low pressure air and causes the loop thrower to drop quickly. FIG. 5 shows a typical arrangement of the wiring of the solenoid coils. The switch 77, which actuates the contactors 62, 63 and 65 and, therefore, energizes the coils 48 and 56, will be associated with a timedelay relay which will permit coil 48 to be energized for only for a time suficient to form a loop. The switch 77 also will be actuated by a photo-cell which indicates the position of the front end of the rod or bar and its entrance into the downstream mill stand thus indicating that it is time for a loop to be formed. Provision should be made for both hand and automatic raising and lowering of the loop thrower. Whether operated automatically or manually, the loop thrower must rise after the front end of the product is in the mill stand following the loop thrower, and the loop thrower must lower before the product leaves the stand preceding the loop thrower. For automatic operation photoelectric relays operating from photocells supply signals to the switches and 77 when the front ends and tail ends of the bars pass the photocell locations. The photoelectric relays initiate adjustable timers which, in turn, operate the loop thrower. The timers must be set by the operator in accordance with the mill speed in the usual manner.

The operation of a front-end photoelectric relay will signal the loop thrower by closing the switch 77 and the operation of a tail end thrower relay will close the switch O 75 and cause the loop thrower to move to its down position. The front end photoelectric relay should be connected to operate only on a light increase and the tail end photoelectric relay should be connected to operate only on a light decrease, thus permitting the relays to reset quickly. This quick reset is necessary because the gap between the tail end of one bar and the front end of the following bar might be very short.

The loop thrower, after being raised, will automatically follow the loop position. This feature will be used to automatically control the height of the loop. The selsyn generator 41 and the tachometer generator 38 are geared to the shaft of the loop thrower for this purpose. The selsyn will be geared in such a manner that a total loop thrower shaft rotation of 45 will cause the selsyn to rotate 180. The selsyn will provide an output voltage signal which is a function of loop thrower position. The output voltage of the selsyn will be zero when the loop thrower is in its down position and the output from the selsyn will be a maximum when the loop thrower is in its extreme raised position. In the preferred embodiment the tachometer generator 38 is geared to the loop thrower shaft 16 to rotate at a speed equal to 35.4 times the shaft speed because of the gear reduction unit 32 interposed between the two. The function of the tachometer generator is to provide a rate-of-change signal to the speed regulator for the following mill stand. The operators control includes the impact loop rheostat 82; without this rheostat the original control will function about as follows:

The operator, for automatic loop control, would set the speed of the stand after the loop thrower to a value less than the matching speed for the stand ahead of the loop thrower. The loop thrower, after raising, would form a loop and follow the loop. The output of the selsyn would rise from zero as the loop thrower rose; the output from the selsyn would cause the speed of the following stand to increase until an equilibrium point was reached. This equilibrium point occurs when the height of the loop thrower is such that the output of the selsyn has increased the speed of the rolling mill stand following the loop thrower until its speed matches the speed of the rolling mill stand preceding. Now, referring to the curve, in FIG. 7, which shows the curve of speed versus time (the dotted line showing the condition without the impact loop adjustment) it can be seen that it was found that the impact speed drop was causing a very high uncontrollable loop to form initially resulting in damage to the product. The impact loop adjustment to rheostat 82 gives the operator a means for controllingn the impact loop. In using the impact loop adjusting rheostat the operator sets the speed of the stand following the loop thrower to a speed higher than the speed required to match the stand ahead of the loop thrower. The impact loop adjusting rheostat is set to cause a decrease in stand speed when the loop thrower is raised simultaneously opening contactor 83 which throws the extra resistance of rheostat 82 into the motor circuit. Thus when the product enters the stand following the loop thrower, the loop thrower rises to develop the required loop and the electrical controls thereafter cause the speed of the downstream rolls to remain at the lower steady state speed reached during impact speed drop. The lower speed would match the speed of the stand ahead of the loop thrower.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all as such properly come within the scope claimed.

The invention having been thus described, what is t3 claimed as new and desired to secure by Letters Patent, is:

1. Means for introducing a loop between the rolls of successive stands in a rod rolling mill, said means comprising electrical circuit means for maintaining the speed of the downstream rolls when the downstream rolls do not have rod passing therebetween higher in relation to the speed of the upstream rolls than the speed required for steady state rolling, an arm having a roller mounted thereon movable transversely of the pass line, a pneumatic linear actuator for moving the arm upward to induce a loop in rod passing through said stands, means for putting said pneumatic linear actuator in operation upon the arrival of the leading end of a new rod at said downstream stand, means actuated by upward movement of said arm after the leading end of the oncoming rod has entered said downstream rolls to vary the electric circuit controlling the speed of said downstream rolls to reduce the speed of the downstream rolls to the required steady state speed called for by the speed of said upstream rolls while said loop is present, means controlled by the position of said arm as it may move in following an increasing or decreasing loop to vary the speed of said downstream rolls to maintain a loop within a determined range of dimensions, and means responsive to detection of the tail end of said rod to lower said arm and reset the downstream rolls to said speed higher than that required for steady state operation after the rod has left said downstream rolls.

2. Means for introducing a loop between the rolls of successive stands in a rod rolling mill, said means comprising electrical circuit means for maintaining the speed of the downstream rolls when the downstream rolls do not have rod passing therebetween higher in relation to the speed of the upstream rolls than the speed required for steady state rolling, an arm having a roller mounted thereon movable transversely of the pass line, a pneumatic linear actuator for moving the arm upward to induce a loop in rod passing through said stands, means for putting said pneumatic linear actuator in operation upon the arrival of the leading end of a new rod at said downstream stand, a high pressure source of air for energizing the actuator with high force for an initial rapid movement in one direction, a low pressure source of air for energizing the actuator with low force for slow movement after the initial rapid movement, means switching the actuator from the high pressure source to the low pressure source after the loop has been formed in the rod, means actuated by upward movement of said arm after the leading end of the oncoming rod has entered said downstream rolls to vary the electric circuit controlling the speed of said down stream rolls to reduce the speed of the downstream rolls to the required steady state speed called for by the speed of said upstream rolls while said loop is present, means controlled by the position of said arm as it may move in following an increasing or decreasing loop to vary the speed of said downstream rolls to maintain .a loop within a determined range of dimensions, and means responsive to detection of the tail end of said rod to lower said arm and reset the downstream rolls to said speed higher than that required for steady state operation after the rod has left said downstream rolls.

References Cited in the file of this patent UNITED STATES PATENTS 1,854,198 Jones Apr. 19, 1932 1,865,941 Michel July 5, 1932 1,866,232 Sykes July 5, 1932 1,956,952 Iverson May 1, 1935 2,087,040 Mican July 13, 1937 2,295,284 McCalfrey et a1. Sept. 8, 1942 2,323,818 Lessmann July 6, 1943 2,569,264 Stone et a1. Sept. 25, 1951 

1. MEANS FOR INTRODUCING A LOOP BETWEEN THE ROLLS OF SUCCESSIVE STANDS IN A ROD ROLLING MILL, SAID MEANS COMPRISING ELECTRICAL CIRCUIT MEANS FOR MAINTAINING THE SPEED OF THE DOWNSTREAM ROLLS WHEN THE DOWNSTREAM ROLLS DO NOT HAVE ROD PASSING THEREBETWEEN HIGHER IN RELATION TO THE SPEED OF THE UPSTREAM ROLLS THAN THE SPEED REQUIRED FOR STEADY STATE ROLLING, AN ARM HAVING A ROLLER MOUNTED THEREON MOVABLE TRANSVERSELY OF THE PASS LINE, A PNEUMATIC LINEAR ACTUATOR FOR MOVING THE ARM UPWARD TO INDUCE A LOOP IN ROD PASSING THROUGH SAID STANDS, MEANS FOR PUTTING SAID PNEUMATIC LINEAR ACTUATOR IN OPERATION UPON THE ARRIVAL OF THE LEADING END OF A NEW ROD AT SAID DOWNSTREAM STAND, MEANS ACTUATED BY UPWARD MOVEMENT OF SAID ARM AFTER THE LEADING END OF THE ONCOMING ROD HAS ENTERED SAID DOWNSTREAM ROLLS TO VARY THE ELECTRIC CIRCUIT CONTROLLING THE SPEED OF SAID DOWNSTREAM ROLLS TO REDUCE THE SPEED OF THE DOWNSTREAM ROLLS TO THE REQUIRED STEADY STATE SPEED CALLED FOR BY THE SPEED OF SAID UPSTREAM ROLLS WHILE SAID LOOP IS PRESENT, MEANS CONTROLLED BY THE POSITION OF SAID ARM AS IT MAY MOVE IN FOLLOWING AN INCREASING OR DECREASING LOOP TO VARY THE SPEED OF SAID DOWNSTREAM ROLLS TO MAINTAIN A LOOP WITHIN A DETERMINED RANGE OF DIMENSIONS, AND MEANS RESPONSIVE TO DETECTION OF THE TAIL END OF SAID ROD TO LOWER SAID ARM AND RESET THE DOWNSTREAM ROLLS TO SAID SPEED HIGHER THAN THAT REQUIRED FOR STEADY STATE OPERATION AFTER THE ROD HAS LEFT SAID DOWNSTREAM ROLLS. 